<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8" />
		<meta name="viewport" content="width=device-width, initial-scale=1">
		<title>web</title>
		<style type="text/css">
			.red{
				width: 300px;
				height: 300px;
				background: red;
				display: none;
			}
			.green{
				width: 300px;
				height: 300px;
				background: green;
			}
		</style>
	</head>
	<body>
		<div class="red"></div>
		<div class="green"></div>
	</body>
</html>